Phosphonates



Unite rates 2,97 3,380 PHOSPHONATES Daniel Swern, Philadelphia, Fa, assignor to the United States of America as represented by the Secretary of Agriculture No Drawing. Original application Jan. 14, 1958, Ser. No. 708,957. Divided and this application Nov. 21, 1958, Ser. No. 779,804

2 Claims. (Cl. 260-403) (Granted under Title 35, U.S. Code (1952), see. 266) (I) a normal alkyl radical containing two through 16 carbon atoms, R is a methyl, ethyl, n-butyl, n-hexyl, Z-ethylhexyl, phenyl or vinyl radical, and R" is a methyl, ethyl, n-butyl or n-hexyl radical, and to hydrolysis products of certain of these a-phosphonates.

One object of this invention is to prepare long-chain trialkyl u-phosphonates, preferably containing a total of at least 15 carbon atoms, for use as plasticizers for polymers such as poly(vinyl chloride) and copolymers of vinyl chloride with vinyl acetate. The term long-chain appears appropriate as the majority of trialkyl a-phosphonates contain one radical with ten to sixteen carbon atoms and all compounds in this group have at least one radical with six or more carbon atoms.

Another object of this invention is to prepare trialkyl a-phosphonates which can be partially hydrolyzed to produce a-phosphonates, or completely hydrolyzed to a.- phosphonic acids useful in making lubricant greases and as adjuncts to detergent formulations, respectively.

A further object is to prepare vinyl esters of alkyl orphosphonates which are useful in making homopolymers and in making copolymers with vinyl acetate, vinyl chloride and other suitably reactive monomers. The copolymers are internally plasticized, thus requiring little or no external plasticizers.

We have discovered that in the preparation of plasticizers having-the general Formula I wherein R is an alkyl radical certain relationships between R, R and R" are important. For example, when R and R" are methyl or ethyl, then R should contain at least ten or seven carbon atoms, respectively, otherwise the products are too volatile for use as plasticizers. When R and R" are n-butyl or higher molecular weight alkyl or aryl groups, R can be methyl or hydrogen, although for convenience in preparation and for low volatility in the product for use as a plasticizer we prefer that R contain at least four carbon atoms. When R contains more than sixteen carbon atoms the volatility of the products is so low that they become diflicult to isolate and purify by high vacuum distillation, or even by molecular distillation, especially when R or R" is n-butyl or higher molecular weight.

F ice Based on studies with over one hundred compounds the longest unsubstituted saturated chain which can be present in a plasticizer to be compatible at the 35% level in poly(vinyl chloride) is about C We have discovered, however, that certain trialkyl a-phosphonates of this invention with an uninterrupted chain .of at least sixteen carbon atoms are primary, eflicient low temperature plasticizers for poly(vinyl chloride).

When R of the general Formula I is a vinyl group the compounds become important as monomers for the preparation of internally plasticized polymers. In these compounds, referring to the general Formula I, R may be hydrogen or an alkyl radical, and R" may be alkyl or aryl radicals.

The a-phosphonates of this invention are prepared in 30 to 96% yields by heating a trialkyl phosphite with the alkyl, aryl, or vinyl ester of an oc-bromo fatty acid as illustrated by the following equation:

The trialkyl phosphites were commercial materials which were fractionally distilled before use: trimethyl phosphite, B.P. 107-9 C.; triethyl phosphite, B.P. 151-5"; and trin-butyl phosphite, B.P. 120-4 at 9 mm. Hg pressure, and tri-n-hexyl phosphite, B.P. l23-6 at 0.15 mm. Hg pressure. Hence R is a methyl, ethyl, n-butyl or nhexyl radical. The methyl or ethyl esters of the u-bromo acids were prepared by refluxing the acid with a five mole excess of absolute methanol or ethanol using an acid catalyst. After several water washes followed by drying, the crude esters were fractionally distilled in an all-glass apparatus. The vinyl a-bromo esters were prepared from the corresponding a-bromo acids by reaction with vinyl acetate using sulfuric acid-mercuric salt as catalyst. The other alkyl a-bromo esters were prepared in the conventional way from the alcohol and oc-bl'OInO acid in the presence of strong acid catalyst with azeotropic removal of water, followed by fractional distillation. Phenyl abromo-stearate was prepared from phenol and a-bromostearoyl chloride in pyridine, in the usual way. This product was also distilled. The esters of a-bromo fatty acids prepared and data pertaining to these compounds are presented in Table I.

TABLE I Esters of ot-bromo fatty acids B.P. Br, Percent u til 0. Mn. Oalcd. Found Ethyl a-brornopelargonate O. 5 1. 4498 30. 1 30. O Ethyl a-bromolaurate 101 0.1 1. 4531 26.0 25. 4 Ethyl oz bromomyristate 128-33 0. 1 1. 4550 23. 8 23. 6 Ethyl a-bromopalmitat 163-6 0.2 1. 4559 Ethyl a-bromostearate. 172-4 0. 2 1. 4570 20. 4 20. 1 Methyl a-bromolaurate. -7 0.05 1.4551 27. 3 27. 3 n-Butyl a-br0mocaprylate. 99-101 0.1 1. 4489 28. 6 28. 4 n-Butyl a-bromolaurate 133 0.3 1. 4535 23. 8 23. 9 n-Butyl a-bromostearate... -60 0. 3 1. 4573 n-Hexyl a-bromocapmate 107-8 1. 6 1. 4505 28. 6 28. 6 z-Etiylhexyl a-bromostearate 187. 91 0.3 1. 4596 16.8 15. l Phenyl a-bromostearate 218-230 0.65 1.485 Vinyl bromoacetate 50-51 9. 0 1. 4692 Vinyl a-bromobutyrate- 63-65 9. 5 1. 4413 Vinyl a-bromohexanoate. 84-86 2. 8 Vinyl a-bromOdecanoate. 92-94 0. 2 1. 4638 28. 8 28. 3 Vinyl a-brom0laurate 116-117 0. 2 l. 4617 26. 2 26. 3 Vinyl a-bromomyristate. 137-139 0.25 1. 4627 24. 0 23. 8 Vinyl a-bromopalmitate. -167 0. 15 1. 4633 22. 1 22. 3 Vinyl a-bromostearate -192 0. 1 l. 4635 20. 5 20. 2

EXAMPLES 1 T0 15 A typical method'of preparation of trialkyl and aryl dialkyl a-phosphonates is as follows: one mole of alkyl or aryl ester of an oc-bIOmO carboxylic acid was heated at MSG-190 C. with two moles of trialkyl phosphite in TABLE II Trialkyl a-phosphonates R"O1 O R" L B. P. Phosphorus, Carbon, Hydrogen, Yield, percent percent percent Example Compound percent 1 m d4 0. mm Calcd. Found Calcd. Found Calcd. Found R=CH3(CH2)01 R=R"RC2H5.... 88 168 4 9.61 9. 81 55.9 54. 8 9.65 9.58 1. 4359 0.9994 R=CH3(OH2)9; R'=R"=C2H5. 80 153-6 0.1 8. 5O 8. 34 59.3 58.3 10.2 10.6 1. 4398 0. 9782 R- CH3(GH2)11; R=R=C2H5 82 173-6 0.1 7.89 7. 74 61. 2 60. 6 10. 5 10.6 1. 4420 0.9658

R=nC4Ho 73 210 0. 18 7. 37 7. 18 62. 8 61. 9 10. 8 10. 7 1. 4413 0. 9547 R=GHa( 2)s; -C2 5;

R=n-C H 53 173 0.25 6. 50 6. 37 65. 5 65.1 11.2 11. 3 1. 4440 0. 9394 R=GH3(CH2)o; R'=R"=n-G4H9. 75 182 0.6 6. 91 7.15 64.3 64.3 11.0 10.7 1.4426 0.9462 R=OH3(OHz)3; R=R"=nOaH 40 139 0.15 6.91 7.45 64.3 63.4 11.0 10.7 1.4405 0.9344 R=CH -(CH2)o; R=R=GH3 61 156 0.7 9.61 9.06 55.9 55.4 9.96 9.71 1.4440 1. 6203 R=CHs(CHz)u; R'=11'C4Hn;

R"=11CnHu 30 16371 0.3 6.91 6.68 64. 3 63.9 11.0 11.2 1.4427 0,9438 R=CHa-(OH2)1s; R=Pheny1;

R"=O H 80 210- 0.4 1.466

TABLE III Comparison of properties of vinyl copolymer (95:5 vinyl chloridewiriyl acetate) plasticized with trialkyl rxphosphonates and commercial plasticizers a Tensile Elonga- Modulus, Clash- Vola- Ex- Trlalkyl a-Phosphonate Strength, tion, 100% Berg tility, ample lb./s q. in. percent lb./sq. in. T-200, Wt. loss,

0. percent Triethyl a-Phosphonostearate 2, 735 330 1, 560 -37 1. 3 Ethyl 1-Dibutylphosphonoflaurate. 2, 570 350 1, 220 42 1. 9 Ethyl (a-Dihexylphosphono)laurate 2, 520 290 1, 390 47 1. 1 Tributyl a-Phosphonolaurate. 2, 800 270 l, 550 43 0.8 Trihexyl a-Phosphonocaproate 2, 550 335 1, 250 7. 3 Butyl (wDiethylphosphonoMaur 2, 200 380 940 -45 5.1 Z-Ethylhexyl (a-Dlethylphosphono 2, 470 340 1,395 41 4.7 Butyl (a-Diethylphosphono)stearate 2, 470 370 1, 240 33 1. 6 Tricresyl Phosphate- 3, 610 270 2, 015 1 0. 3 Triphenyl Phosphate 3, 290 320 1, 450 -8 Oresyl Diphenyl Phos 3, 335 265 l, 610 7 1. 1 Alkylarylphosphate 2, 560 310 1, 215 28 2. 3 Di(2-ethylhexyl) Phthalate 2,930 370 1,390 -28 1.1

1 Recipe: Copulymer 63; plastieizer 35; stabilizers and mold release agents 2.

an atmosphere of nitrogen. The alkyl bromide formed during the reaction was swept out and collected in a Dry Ice, trap. The reaction was stopped when the weight of alkyl bromide become constant (usually 4 to 5 hours). The entire reaction mixture was then fractionally distilled to recover unconsumed trialkyl phosphite and to isolate the pure m-phosphonate. The trialkyl or aryl dialkyl unphosphonates, further identified and characterized by the data presented in Table H, are high-boiling, colorless, odorless, thermally stable liquids, insoluble in water and soluble in organic solvents.

The trialkyl a-phosphonates of the general Formula I having relationships of R, R, and R" as previously discussed, are efficient, primary plasticizers for poly(vinyl chloride) and copolymers of vinyl chloride with vinyl acetate. At the 35% level. they impart good mechanical properties to the plasticized material and they are good Comparative data for some commercial plasticizers are also included in Table III. p

Inspection of the data reveals that these trialkyl ocphosphonates are superior to some of the most important commercial plasticizers because they impart excellent low temperature properties, in most instances they give superior mechanical properties, and their volatility characteristics are adequate. Examples 5, 12 and 13 illustrate the first time a compound containing an unsubstituted saturated chain of at least 16 carbon atoms is used as a primary, efiicient low temperature plasticizer. I In addition to their use as plasticizers, the trialkyl ocphosphonates are also useful as intermediates for the prep aration of a-dialkylphosphonocarboxylic acids and aphosphonocarboxylic acids. Upon partial or complete hydrolysis of trialkyl a-phosphonates, the phosphoruscontaining group remains attached to the fatty acid chain.

The result of selective hydrolysis of the carboxylic ester group with dilute base is an a-dialkylphosphonocarboxylic acid, represented by the Formula II, and complete hydrolysis of the three ester groups of a trialkyl a-phosphonate by refluxing with 20-35% hydrochloric acid is a tribasic a-phosphonocarboxylic acid, represented by the Formula III.

R-( JH()-0H HO-POH .L 0

In a typical procedure for the preparation of com- EXAMPLES 16 '10 23 Vinyl a-dialkylphosphonates were prepared by the reaction of appropriate trialkyl phosphites with the vinyl esters of a-brornocarboxylic acids of Table I using essentially the same procedures described for the preparation of the compounds of Examples 1 to 15. The characteristics of these vinyl esters are summarized in Table V.

TABLE IV Neutralization equivalent of a-diethylphosphonomonocarboxylic acids obtained by partial hydrolysis of triethyl a-phosphonates pounds of the formula H approximately 0.5 to 1 gram Neut. Equlv. of of a tnethyl a-phosphonate was refluxed for one hour Isolated Add with 25 ml. of 0.2 N potassium hydroxide in 95% eth- Tnethylao p o te sedasflta t aterial anol. The solution was acidified with hydrochloric acid 25 Calm Found and the reaction mixture was evaporated to dryness. The residue was washed several times with ether and Table I'Emmnle 294 297 the combmed ether solut1ons were filtered to separate 1nl. 3%: soluble salt. Evaporation of the ether fromfhe filtrate 1 fl g 392 396 yielded the a-d1ethylphosphonocarboxylie aCld, charac- Table LE mplefi 420 417 terized by its neutral equivalent. The compounds of Ex- TABLE V Vinyl a-dialkylphosphonates B. P. Phosphorus, Carbon, Per- Hydrogen, Yield Percent cent Percent. ample Compound Pig; an m "0 mm. Caled. Found Calcd. Found Calcd. Found 16.- 15:13;R'=v1n 1;n"=c,r1 41 96-100 0.25 13.94 14.22 43.2 V 42.3 6.8 7.0 1.4348 1.1245 17. R=CH1CH2; R=Vinyl; M01115--- 34 133-134 7.0 1.4368 1.0761 18 hOH;-(OH2)a;R/=Vinyl;R=C2 38 158-159 7.8 1.4370 1.0436 19 R=CH:(CH2)7; R=Vinyl; R"=C1H5 62 146-8 0.15 9.26 8.76 57.5 57.3 9.4 9.7 1.4423 0.9990 20 R=OH;--(OH9):; R=Vinyl;R"=C2Hs 47 152-3 0.05 s. 55 8.78 59.6 59.1 9.7 9.7 1.4443 0.9836 21- R=CHF(OH2)11;R=Vinyl;R=O H 39 172-4 0.15 7.93 7.93 61.5 60.7 10.1 10.0 1.4459 0.9736 22 R=CH;-(CH2)13;R=Vinyl;R=O H 73 200-2 0.10 7.40 7.53 63.1 62.5 10.4 10.3 1.4478 0.9659 23..- B=OH -(GH1)15;R=Vinyl;R"=C4H 43 204-6 0.05 6.94 7.33 64.5 63.2 10.6 10.9

amples 1 to 5 were hydrolyzed according to this pro- I claim:

1. u-Phosphonolauric acid. 2. a-Phosphonostearic acid.

References Cited in the file of this patent UNITED STATES PATENTS Wiley Aug. 9, 1949 OTHER REFERENCES Ackerman et 31.: J. Am. Chem. Soc., 79, 6524-6525 (1957). 

1. A-PHOSPHONOLAURIC ACID. 